Recently, in hospitals or the like, there is an increased need for performing various treatments such as separation, extraction, inspection, and measurement of minute substances such as bacteria (for example, protozoa, and bacteria dissolved in water, such as colon bacillus such as O157 and O26, Legionella bacteria, cryptosporidium bacteria, salmonella, dysentery bacillus, and Campylobacter bacteria).
Particularly, reports of accidents and cases of diseases due to Legionella bacteria have been increasing rapidly. Legionnaires' disease was specified as a category 4 infection by the “Law Concerning Prevention of Infections and Medical Care for Patients of Infections” (new law for infection control) in December 1998, and has a risk of death for aged people and people in an immunological deficiency state or in a state with resisting power being weakened. Therefore, investigation into the cause thereof, and stable detection and rapid detection of Legionella bacteria have been desired.
The microbes such as bacteria are generally obtained in a condition where a minor amount of microbes are suspended in a large amount (for example, from about 50 mL to about 10 L) of liquid (for example, blood, juice, feces, or sewage). Various treatments such as culturing and amplification of the microbes and PCR for detecting O antigens or Verotoxin (VT) genes need to be performed in a state with the concentration of the microbes being increased.
Regarding Legionnaires' disease, for example, according to “New Guidelines for Prevention of Legionnaires' Disease”, chlorination needs to be performed immediately, when an inspection result is 1 cfu/100 ml (cfu: colony forming unit) in an inspection of environmental water in a bath or the like, which a human body directly touches, or when an inspection result is 10 cfu/100 ml in an inspection of environmental water in a cooling tower or a heat storage tank. In order to detect the borderline, enrichment of Legionella bacteria from a large amount of samples such as several hundred milliliters is required.
Conventionally, therefore, separation and extraction have been performed by causing a large amount (for example, more than 1 liter) of suspension in which the microbes are suspended, to pass through a barrier filter or sterilization filter, or by centrifugal separation, or by culturing in a medium. Generally, however, the suspension contains a large number of impurities other than the target. Because there is such cloudiness and contamination in the suspension, when the barrier filter or sterilization filter using a pore size smaller than the biomass is a membrane filter or the like, inefficiency has been frequently pointed out, and there is a disadvantage in that these filters are blocked or undesired substances are collected. Moreover, when centrifugal separation is used, it is normal that centrifugal separation is performed for 10 minutes at a speed of 11000 rpm, for example, by obtaining 1 mL of a sample in a tube, and it is difficult to handle a large amount of liquid of more than 1 liter at a time in view of equipment size. Thus, conventionally, it has been difficult to separate a target from a large volume of suspension, and time and labor are required.
Moreover, taking into consideration the case where substances such as bacteria that affect living things such as humans are handled, an apparatus has been desired that can automatically perform treatment without the need of human operation, portions in contact with the suspension can be replaced without the need of washing, and it can be used efficiently and reliably.
To capture microbes or the like such as bacteria, it is known that capturing efficiency can be increased by using a capturing material of an appropriate size corresponding to the size of the bacteria.